Table 2. Analysis of N-glycan structures. The majority of N-glycan structures detected after desialylation were complex-type
biantennary structures without terminal Gal (36.6%), with one terminal Gal (44.9%) and with two terminal Gal (15.1%). Approximately
2% of the N-glycan structures were still sialylated. This analysis shows that transiently transfected HEK293 cells have the
ability to synthesize N-glycan structures similar to those obtained from CHO cells.
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After a highly purified product was obtained, the glycosylation patterns were analyzed by looking at N-glycan structures released
from the antibodies (Table 2). This analysis confirmed the ability of the transiently transfected HEK293 cells to synthesize
N-glycan structures similar to those obtained after stable expression (e.g., in CHO cells). This study showed that the antibodies
produced in serum-free conditions using a multi-tray bioreactor were of equal quality to antibodies produced in suspension
CHO cells.
IQ Therapeutics BV
In a third study, IQ Therapeutics BV, a Dutch biotechnology company engaged in discovering and developing antibodies for therapeutic
use in infectious diseases and for biodefense, uses multi-tray bioreactors (Nunc Cell Factory, Thermo Fisher Scientific) to
quickly generate sufficient volumes of antibody material for animal studies. IQ has two monoclonal antibodies for anthrax
in preclinical studies. The two antibodies are directed against two components of anthrax's lethal toxin: The antibody IQNPA
is directed against protective antigen, and IQNLF is directed against lethal factor. Currently, IQ uses multi-tray bioreactors
to produce these antibodies for preclinical studies in animal models. Production for clinical trials, however, is outsourced
to a contract manufacturing operation to ensure compliance with current good manufacturing practices.
For in-house production using human hybridomas, IQ began to use multi-tray units instead of standard flasks. After investing
some time to optimize the use of the multi-tray bioreactors, IQ researchers found conditions in which IQNPA antibody production
improved by more than 30% and IQNLF antibody production more than doubled (+120%), compared to 175-cm2 flasks.
The team at IQ found the system effective and easy to use. "The ten tray cell culture system is very effective in manufacturing
75 mg batches of antibody," said Herman Groen, PhD, the CSO of IQ Therapeutics. "That is sufficient material to do a lot of
in vitro functional studies, as well as work in animal models." Hans Westra, responsible for manufacturing at IQ, notes that his team
also benefited from simplified protocols when dealing with this type of technology. "The very short time we needed to become
accustomed to handling the multi-tray bioreactors made the adaptation of the production process into our facility very easy,"
he said.
On the Horizon
The evolution of the multi-tray cell culture system for adherent cell line production was enabled by improving upon an existing
device, the 175-cm2 flask. The need to scale up adherent cell propagation pushed researchers and engineers to improve upon this technology to
create the multi-tray format. The future success of this type of format, however, will be contingent upon continuous innovation
and improvement. For example, the application of various surface treatments will help cells adhere to the inner walls of a
tray in a stronger and more specific manner. Also, developing multi-tray bioreactors as completely closed systems with customized
tubing configurations to facilitate and control the flow of liquids and gases within the interior environment is under way.
A closed system like this would provide sterility, flexibility, and speed for vaccine development and production.
Edwin Schwander is the market development manager at Thermo Fisher Scientific, Roskilde, Denmark, +31.6.51541921, e.h.schwander@home.nl
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